EM122 Water Column Sonar Data Collected During AT26-02

Cascadia Initiative Year 3, LEG 3 (At26-02, EM122). Recover 30 Lamont Doherty Earth Observatory Ocean-bottom Seismometers (OBSs) of 3 different types: •10 TRM shallow-water OBSs with Trillium compact 3-component absolute pressure gauge installed at depths from 200-1000m (nominal). Recovered using remotely operated vehicle Jason. •10 Trawl-Resistant Mount (TRM) shallow-water OBS with Trillium compact 3-component seismometer, absolute pressure gauge (APG), acoustic release/pop-up buoy with Jason backup. •10 LDEO deep water OBSs with APG. Recover by sending an acoustic release command to drop the anchor. OBS then floats to the surface a nominal rate of 50m/min. Referred to as LDEO-DW below. •Iftime allows, discover and recover 2 Woods Hole Oceanographic Institution deep water OBSs. Additional Activities: Acquire swath bathymetry, including water column data, in transit between all stations and port. Acquire other underway data (e.g. meterology, acoustic doppler current profiler).